Abrading tool having suction system for collecting abraded particles

ABSTRACT

A portable tool for sanding or otherwise abrading a work surface and having an air motor which drives the abrading part or unit, with an air suction system being provided for sucking dust and other abraded particles from the work surface to prevent their escape into the surrounding air, and with the suction effect desirably being created by energy derived from the exhaust of the air motor, preferably through an aspirator action.

States Patent [191 Hutchins ABRADING TOOL HAVING SUCTION SYSTEM FOR COLLECTING ABRADED PARTICLES [76] Inventor: Alma A. Hutchins, 49 N. Lotus Ave., Pasadena, Calif. 91 107 [22] Filed: Dec. 28, 1971 21 App]. No.: 213,013

[52] US. Cl. 51/170 MT, 51/273 [51] Int. Cl B24b 23/00, -B24b 55/06 [58] Field of Search 51/170 T, 170 TL,

[5 6] References Cited UNITED STATES PATENTS 2,143,970 1/1939 Blood 5'1/170 T 5/1935 De Nagy 51/170T [111 3,785,092 [451 Jan. 15, 1974 1,800,341 4/1931 Davies 51/170 T 2,929,177 3/1960 Sheps 51/170 MT 2,764,852 10/1956 Emmons 51/273 X 3,638,362 2/1972 Stoll .1 51/273 2,499,933 3/1950 Smul 51/273 X Primary Examiner-James L. Jones, Jr. AttorneyrWilliam P. Green 57] ABSTRACT A portable tool for sanding or otherwise abrading a work surface and having an air motor which drives the abrading part or'unit, with an air suction system being provided for sucking dust and other abraded particles from the work surface to prevent their escape into the surrounding air, and with the suction effect desirably being created by energy derived from the exhaust of the air motor, preferably through an aspirator action. 0

16 Claims, 11 Drawing Figures SHEET 3 BF 3 PATENTEUM 15 1914 I I O4 INVENTOR.

w H m. u H A K L A ABRADING TOOL HAVING SUCTION SYSTEM FOR COLLECTING ABRADED PARTICLES BACKGROUND OF THE INVENTION This invention relates to improved portable work abrading tools, such as for example sanding tools or the like.

In using a portable sanding tool or the like, the abrading material or element inherently tends to produce substantial quantities of particles abraded from the workpiece and forming essentially a dust-like mass covering the workpiece and tool and escaping into the air. This dust interferes with the sanding operation, and can be both unpleasant and physically harmful to the operator bf the tool, who is forced to breathe the air into which the dust escapes. Attempts have been made in the past to provide means for collecting the produced dust, but all such prior arrangements of which I am aware have resulted in an overall tool assembly which was unduly complicated and expensive to manufacture, and very cumbersome to handle.

SUMMARY OF THE INVENTION The present invention provides a unique abrading tool in which the produced dust can be collected with maximum simplicity of structure and operation. In spite of this simplicity, however, the dust removing action is extremely positive and complete, and is adapted for reliable operation substantially indefinitely and with a minimum of repair.

Many of the advantages of the tools embodying the invention are attained by employing a motor of a type in which a stream of air flows through or past the motor in operation, and by then utilizing that flow of air after it leaves the motor as a source of energy for producing a suction effect acting to withdraw the abraded particles from the vicinity of the work surface. Preferably, the air flow is passed through a simple aspirator, which produces the desired suction by aspirator action and then blows the withdrawn dust or particles into a collection bag or other container. In the optimum arrangement, the motor is of an air driven type, so that a single flow of compressed air can function first to drive the motor and then produce the suction effect. In such a system, the connection of the suction equipment into the exhaust line from the air motor also attains a highly beneficial secondary result of essentially silencing or substantially muffling the sound produced by the air motor.

The actual work abrading operation can be performed by a power driven shoe or unit, which can be driven either orbitally, reciprocally, rotatively, or in any other desired mode relative to the body of the tool, to perform the sanding or other abrading function. Desirably, this power driven unit contains a passage or passages through which the abraded particles can be drawn from the workpiece by the suction apparatus, with a sheet of sand-paper or the like preferably being carried by the power driven unit and containing apertures communicating with the mentioned suction passages to place the suction effect right at the work surface. For best results, the mentioned passages may be formed directly in and extend through a cushioning deformable pad portion of the movable abrading unit.

Certain additional features of the invention relate to the provision of a shroud about the abrading unit in some forms of the invention, with the shroud projecting into close proximity to the work surface to define an essentially closed space through which the dust collecting suction is communicated to the work surface. The shroud may be formed of a deformable material, and desirably is mounted for adjusting movement toward and away from the work surface to assure proper engagement therewith and to compensate for use of abrading heads of different thicknesses.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and objects of the invention will be better understood from the following detailed description of the typical embodiments illustrated in the accompanying drawings in which:

FIG. 1 is a side view of a first form of sanding tool constructed in accordance with the invention;

FIG. 2 is an enlarged side view of the FIG. 1 tool, partially broken away to reveal some of its inner construction;

FIG. 3 is a plan view taken primarily on line 3-3 of FIG. 2;

FIG. 4 is an enlarged fragmentary vertical section through the aspirator and taken on line 44 of FIG. 3;

FIG. 5 is a horizontal section taken on line 5-5 of FIG. 2 and showing the pattern of air passages in the sandpaper engaging cushion of the device;

FIG. 6 is a bottom plan view taken on line 66 of FIG. 2;

FIGS. 7, 8, and 9 are perspective representations of three other forms of the invention;

FIG. 10 is primarily a vertical section through the tool of FIG. 9; and

FIG. 11 is a reduced bottom plan view taken on line l111 of FIG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first illustrated form of the invention, shown in FIGS. 1 to 6, takes the form of a power operated sander 10, for abrading and smoothing a work surface typically represented at 11 in FIG. 1. The tool is manipulated by hand over the work surface, and includes a collection bag 12 into which particles or dust abraded from work surface 11 are drawn by suction.

As seen best in FIG. 2, the tool includes a main portable body 13 having appropriate handles by which a user can grasp and carry the tool, and move it over the work surface 11. These handles may include a rearwardly projecting handle 14 and a forwardly and upwardly projecting knob 15 to be grasped by the two hands of the operator. Body 13 may have a lower essentially rectangular portion 16 which in the FIG. 2 position extends horizontally and may have a peripheral depending flange 17. At the center of its lower horizontal portion 16, body 13 may have an upwardly projecting hollow portion 18 connected to handle 14 and containing an air motor 19 having a driven shaft 20 turning about a vertical axis 21. The motor 19 may be of any conventional type, but preferably is a vane type motor, as seen partially in FIG. 3, including an outer cylindrical nonrotating housing part 22 securedto body 13 in fixed position relative thereto, and a rotor 23 located eccentrically within a cylindrical chamber in part 22 and mounted to turn relative thereto about the previously mentioned vertical axis 21. A series of circularly spaced radially extending vanes 24 are movably contained within slots in rotor 23, to define a series of compartments which change progressively in size as the rotor turns. Compressed air from a source represented at 26 in FIG. 1 is fed through a flexible supply hose 27 and passages contained in handle 14 and part 22 to compartments 25, to cause rotation of rotor 23 about axis 21. After thus driving the rotor, the compressed air is exhausted from the interior of part 22 through a discharge opening 28 formed in a side of part 22 and communicating with a tube 29 of an aspirator 30 which will be described in greater detail at a later point. The air as it leaves the motor and passes into and through tube 29 is still at a substantially superatmospheric pressure, say for example about 70 pounds per square inch, to move rapidly through tube 29 in a manner attaining an effective aspirator action. The delivery of compressed air to the motor may be controlled by a valve 31 contained within handle 14, and actuated between closed and opened positions by a finger operated trigger element 32 carried at the underside of the handle.

At a location spaced beneath and parallel to portion 16 of body 13, this body movably carries an orbitally moving unit or assembly 33 which is power driven by motor 19 and carries at its underside a rectangular downwardly facing sheet of sandpaper or other abrasive material 34. As seen in FIG. 2, unit 33 includes a rigid shoe element 35 preferably formed of sheet metal and which has a main planar horizontal rectangular portion 36 (FIG. 3) typically reinforced by parallel upstanding flanges 37 formed along its opposite sides. At its underside, shoe 35 removably carries a rectangular pad assembly 38, including a layer of resiliently deformable rubber or other cushioning material 39 appropriately adhered by suitable cement or the like to a more rigid typically sheet metal plate 40 extending across the upper side of cushion 39. Two releasable spring actuated clips 41 may be carried at the upper side of portion 36 of shoe 35, near the opposite ends thereof, for engaging and releasably retaining opposite ends of the sandpaper sheet 34, with the main portion of the sandpaper sheet extending horizontally along the horizontal undersurface 42 of cushion 39. The sandpaper is thus pressed yieldingly downwardly by the cushion and the weight of the tool against work surface 11, in a planar condition, to perform an effective sanding operation on the work surface.

Shoe 35 and the carried pad assembly 38 and sandpaper sheet are driven orbitally by motor 19 through a downwardly projecting lower end portion 43 (FIG. 2) of motor shaft 20, which portion 43 may be externally cylindrical but have its vertical axis 44 offset laterally from and parallel to the main vertical axis 21 of the motor. This eccentric lower portion 43 of shaft 20 extends downwardly within the inner races of a pair of ball bearings 45 whose outer races are confined in fixed position relative to shoe 35 by reception within a hollow housing 46 attached to the shoe. Thus, as shaft 20 turns about axis 21, the lower portion 43 of the shaft moves orbitally about axis 21 and causes corresponding orbital movement of shoe 35 and the carried pad assembly 38 and sandpaper. At the same time, however, the shoe and carried parts are retained against rotation about vertical axis 21 by four flexible resilient essentially vertical connector posts 47, desirably formed of rubber or the like, and having sufficient stiffness to retain the shoe in an essentially fixed orientation with respect to the body 13, while at the same time permitting the desired slight captive orbital movement of the shoe relative to the body. The upper ends of posts 47 can be connected to portion 16 of body 13 by screws 48 extending downwardly into connector nuts 49 molded into the upper ends of the posts. Similarly, the lower ends of the posts may be secured to shoe 35 by screws 50 extending upwardly through portion 36 of the shoe and into nuts 51 molded into the lower ends of posts 47.

As seen in FIGS. 5 and 6, the deformable cushion 39 which backs up sandpaper sheet 34 contains a number of spaced apertures 52 which extend upwardly through the cushion and function as suction lines for drawing abraded particles away from the work surface 11. The sandpaper sheet 34 contains the particles same number of apertures 53, registering with apertures 52, to pass FIG. 4) abraded particles upwardly through the sandpaper into apertures 52. In the particular arrangement illustrated in FIGS. 5 and 6, there are 10 of these apertures in each of the elements 39 and 34, preferably arranged in two spaced rows each including five apertures.

The upper surface 54 of cushion 39 is planar and parallel to undersurface 42 except for the provision of a number of intercommunicating recesses or grooves 55 formed in upper surface 54 and communicating at their ends with apertures 52 (see FIG. 5). These grooves 55 conduct suction air and abraded particles from apertures 52 to the location of an opening 56 (see 1 10.4

formed in horizontal plate 40. As will be apparent, plate 40 closes the upper side of grooves 55 except at the location of the aperture 56, and is cemented to surface 54 of cushion 39 entirely about all of the grooves 55 and apertures 52 and about opening 56, in air-tight sealed relation preventing leakage of any air into or out of grooves 55 except through opening 56 or apertures 52. As seen in FIG. 2, the pad assembly 38, including cushion 39 and plate 40, is detachably secured to the underside of shoe 35 by the same screws 50 which attach the shoe to deformable posts 47. To allow access to the heads of screws 50, cushion 39 may contain additional apertures 57 at the locations of these screws through which a screwdriver may extend upwardly into engagement with the screws.

The suction air and entrained dust are drawn up wardly from apertures 56 of FIG, 4 into a flexible vertically extending tube 58, typically formed of an appropriate flexible resinous plastic material such as a suitable vinyl or the like. The lower end of this tube 58 may be a tight fit about a short cylindrical upwardly projecting tube 59 secured to and projecting upwardly from shoe 35 at a location of alignment with and communication with aperture 56 in plate 40 of the pad assembly. At its upper end, tube 58 is similarly received tightly about a downwardly projecting externally cylindrical portion 60 of a main tube or conduit of the previously mentioned aspirator 30, which aspirator is secured in fixed position to body 13. The tight frictional engagement of flexible tube 58 with the rigid tubular elements 59 and 60, with resilience of the material of tube 58 tending to constrict this tube inwardly against the outer surfaces of tubes 59 and 60, forms two annular airtight seals at the upper and lower ends of tube 58, while at the same time allowing slight orbital deformation of tube 58 in correspondence with the oribital movement of shoe 35 and with the deformation of posts 47.

In extending upwardly above its point of sealed connection to flexible tube 58, the main rigid tube 160 of aspirator 30 first extends upwardly through an aperture 260 in portion 16 of body 13, and then forms a right angle elbow which curves horizontally at 61 (leftwardly as viewed in FIG. 4) to define a straight cylindrical horizontally extending portion 62 of tube 160 centered about a horizontal axis 63. Beyond straight cylindrical portion 62, tube 160 of aspirator 30 has a frustoconically flaring annular portion 64, still centered about axis 63; and beyond this flaring portion the side wall of the tube may have a second straight cylindrical portion 65, of an increased internal diameter as compared with that of portion 62.

The previously mentioned tube 29 which communicates with the air outlet 28 of motor 19 extends through an opening in the tube 160 at 66, in sealed relation with respect thereto (or may be molded or cast integrally with tube 160), and then continues within portion 62 of tube 160 in concentric relation with respect thereto, that is, along the axis 63 of portion 62, with an annular air passage or space 67 being provided between tube 29 and portion 62. Desirably, the tube 29 continues leftwardly to a point at least partially within the frustoconical flaring portion 64 of the outer wall of the aspirator, and for best results terminates in the transverse plane 68 at which the flaring portion 64 reaches its maximum diameter. It is also helpful if the end portion of tube 29 tapers frustoconically, as shown at 129 in FIG. 4, desirably within the flaring portion 64 of the outer tube.

A short distance beyond flaring portion 64, the portion 65 of the outer tube of the aspirator is connected to a flexible hose 69 which extends along and generally parallel to the air inlet hose 27, and which terminates at 70 (FIG. 1) within the dust collection bag 12. Bag 12 is formed of an appropriate porous material, preferably woven material of the type commonly utilized in vacuum cleaners and the like, adapted to pass through the material of the bag to its exterior the air exhausted from the air motor, while having a close enough weave or pore pattern to prevent the abraded dust particles from the work surface from leaving the bag with the air. The material forming the bag may be double stitched along two parallel lines 71 and 72 near its upper edge, to define an elongated passageway within which hose 27 may pass, to thereby support bag 12 from hose 27. A tie string 73, clamp or other attaching element may be carried by the bag at its leftward end in FIG. 1, and be tightenable about both of the tubes 27 and 70 to form an airtight closure of the bag at that location. Similarly, another tie string 74 or its equivalent may be provided at the second end 75 to close that end of the bag about hose 27, while at the same time allowing emptying of the bag from its right end by loosening of the tie string 74.

To now describe the manner of use of the tool of FIGS. 1 to 6, assume that the tool is assembled as illustrated in FIG. 1, and that the air supply hose 27 has been connected at 76 to a hose 77 leading from compressed air source 26. Assume also that the sandpaper sheet has been connected by clamps 41 to the shoe of the device as illustrated in FIG. 2. An operator then grasps the tool by its two handles 14 and 15, and places the tool on the work surface 11 in the FIG. 1 position, and then actuates trigger 32 to admit air from source 26 to motor 19. This air acts against the vanes 24 of rotor 23 to cause rapid rotation of the rotor about axis 21, and shaft 20 then acts through its eccentric portion 43 to orbitally oscillate the shoe unit or assembly 33 and carried sandpaper 34 relative to body 13 of the device. This oscillatory motion abrades the work surface 11, and smooths that surface, but at the same time produces a dust on the surface composed of particles abraded from the work-piece. These dust particles are drawn upwardly through apertures 53in the sandpaper sheet, and through apertures 52 in cushion 39, into passages 55 of FIG. 5. From these passages, the suction flow of air and particles moves upwardly through tube 58 of FIG. 4, and then advances first upwardly and then horizontally through portions 60, 62, 64, and 65 of conduit 160, for ultimate discharge through flexible hose 69 into bag 12, in which the dust particles are entrapped while the air escapes through the porous wall of the bag.

As previously indicated, this movement of suction air is produced by aspirator action, as a result of the rapid movement of air exhausted from motor 19 leftwardly in FIG. 4 through tube 29, and into the end portion 65 of the outer tube of the aspirator. The rate of discharge of this air from the end 129 of tube 29 is sufficiently rapid to attain a very effective aspirator action, and to produce a subatmospheric partial vacuum at the work surface adequate to effectively withdraw all of the produced dust from the work surface by suction. In addi tion, the provision of the aspirator and dust collection bag 12 in the path of the exhaust air from motor 19 serves the additional function of very substantially reducing the amount of noise produced by the air motor, since the air is no longer exhausted from that motor directly into the atmosphere.

FIG. 7 shows the manner of application of the present invention to a sanding tool 10a which is very similar to that of FIGS. 1 to 6, except that the upwardly projecting portion of the body 15a of the tool serves itself as the handle of the device, with the air inlet valve being actuable by downward deflection of an upper platelike element 32a. With this body and handle arrangement, the aspirator 30a may be located at a laterally central position, essentially directly beneath the air inlet line 27a and the air inlet portion 127a of the tool body, rather than at a laterally offset position as in FIG. 3. The exhaust air from the air motor within body 13a may be led by a suitable tube represented at 29a into the interior of the aspirator. The orbitally movable sandpaper carrying shoe assembly or unit 33a may be mounted and driven in essentially the same manner as in FIGS. 1 to 6, with suction air being drawn by aspirator 30a from the work surface through apertures and passages formed in the shoe assembly, and apertures in the sandpaper, as previously discussed. The interior construction of the aspirator 30a may be essentially the same as described in connection with FIG. 4, to attain the same type of suction effect by aspirator action.

FIG. 8 illustrates diagrammatically the application of the present invention to an in-line type of sanding tool 10b, in which the sandpaper carrying shoe assembly 33b is mounted to the hand carried body 13b of the device for straight line reciprocating motion along axis 77 parallel to the work surface and relative to body 1019. An air driven motor 13b within body 10b acts through an appropriate drive mechanism to produce such reciprocating relative motion of the shoe assembly. The sandpaper 34b contains apertures corresponding to those shown at 53 in FIG. 6, communicating with registering apertures and passages in rubber pad 39b, as illustrated at 52 and 55 in FIGS. and 6, with these suction apertures and passages leading into an aspirator b into which exhaust air from motor 19b is led through a tube 29b. Aspirator 30b functions in essentially the same manner as aspirator 30 of FIGS. 1 to 6, to produce a suction at the underside of shoe assembly 33b resulting from the aspirator action of the rapidly moving exhaust air from line 29b, causing air and dust particles to be drawn through hose 69b into a collection bag such as that shown at 12 in FIG. 1. As in FIG. 1, this suction system keeps the work surface clean, prevents escape of the produced dust particles into the air, and muffles the sound produced by motor 19b.

FIGS. 9, l0, and 11 show another sanding tool embodying the invention, including a hollow handle body 81 externally contoured to be easily grasped by a user. This body 81 contains a rotary preferably vane type air motor 82 having a rotor 83 driving a shaft 84 about a vertical axis 85 relative to body 81. Compressed air is supplied to the motor through an inlet hose 86 from a compressed air source 87. The air exhausted from the motor after driving its rotor 83 discharges through an outlet tube 88 which may connect into a side of handle body 81 and extend downwardly therefrom to the location of an aspirator 89. This discharging air in exhaust line 88, even after passing through and driving the motor, is still at a substantially superatmospheric pressure, say for example about 70 p.s.i.

At its lower end, shaft 84 of the motor drives a removable circular sanding head 90, which is driven orbitally with respect to axis 85. For this purpose, the lower end of shaft 84 has an eccentrically offset externally cylindrical portion 91 whose axis 97 is parallel to but offset from axis 95. Shaft portion 91 is received within and secured to the inner races of two aligned ball bearings 92, whose outer races are contained within and connected to a hollow cylindrical part 191, to mount that part and a connected circular member 93 for rotation relative to eccentric portion 91 of the shaft and about axis 97. The circular head has an upwardly projecting externally threaded screw or stud 94 which is removably connectible into an internally threaded bore 95 in member 93 centered about axis 97,

to secure the head 90 thereto. Head 90 may have a rigid circular backing plate 96 disposed transversely of and centered about axis 97 of screw 94 and shaft portion 91, with a resiliently deformable cushion of rubber or the like 98 being positioned at the forward side of backing plate 96, and being circular and centered about axis 97, to carry and back up a correspondingly circular disc 99 of sandpaper. This paper may be secured in any manner to the front face 198 ofcushioning material 98, as by an appropriate adhesive. As a result of this discussed mounting of head 90, the head and carried sandpaper disc rotate orbitally about main axis 85 of motor 82 as the motor is driven.

Beneath the level of motor 82, body 81 of the tool rigidly carries a downwardly projecting rigid annular cylindrical flange or skirt 100, centered about the main axis 85 of the motor and tool, and secured appropriately to body 81 as by screws 101 extending upwardly through an annular inturned horizontal flange 102 of part 100. To the outside of part 100, there is mounted a shroud 103, which may be formed of a resiliently deformable material, such as a suitable rubber, and which flares downwardly and outwardly to an increased diameter lower circular edge 104 of the shroud for annularly engaging a work surface 105 at a location about and spaced outwardly from sanding head 90. Edge 104 is desirably positioned to lie in the transverse plane 204 of sandpaper 99, which plane is perpendicular to axes 85 and 97. In some arrangements, the upper circular edge portion 106 of annular shroud 103 may be permanently secured in fixed position relative to part 100, to thereby tend to locate edge 104 of the shroud in a correspondingly essentially fixed position, from which it can be displaced only by deformation of the material of the shroud. Preferably, however, the entire shroud 103 is mounted for limited upward and downward movement relative to part 100 and sanding head 90 and along axis 85 of the tool, as by connecting the upper edge 106 of the shroud to an annular more rigid part 107, typically formed of metal or the like, with this part 107 being a fairly close fit on the outer cylindrical surface of part 100, but being movable upwardly and downwardly on part 100 with shroud 103 to raise and lower the shroud relative to sanding head 90. This upward and downward movement of the shroud relative to the tool body and head 90 allows the lower edge 104 of the shroud to always fall by gravity into annular contact with work surface 105, and additionally allows the shroud to be adjusted upwardly and downwardly to compensate for use of sanding heads 90 having different effective vertical thicknesses.

The aspirator 89 includes a main outer tube 108 whose left end as viewed in FIG. 10 is connected at 109 into a side of cylindrical flange part 100, to communicate with the interior of that flange part and the interior of shroud 103. Tube 108 may have a first straight cylindrical portion 110 centered about a horizontal axis 111, and merging into a frustroconically flaring portion 112 and then a second straight cylindrical but increased diameter portion 113, with these latter two portions 112 and 113 also being centered about axis 111. The air exhaust tube 88 from air motor 82 extending through a side wall of tube 108, and then forms a tube 114 extending along and centered about axis 111 and spaced radially from the wall of tube 108 to form an annular space 214 through which air and dust particles from within the shroud can move leftwardly in FIG. 10 under aspirator action. Desirably the extremity 115 of tube 114 terminates in essentially the same transverse plane 116 in which frustoconical portion 112 of tube 108 reaches its maximum diameter. At its left end, tube 108 is connected to a hose 117 leading to a dust collection bag 118 or the like, formed ofa porous material through which air can escape from the bag while entrapping the abraded particles from work surface 105 in the bag.

The dust produced by abrasion of surface 105 is withdrawn upwardly within shroud 103 through the space 119 about head 90, and also through a series of circularly spaced apertures 120 extending upwardly through the head, including both its backing plate 96 and cushion 98. Corresponding apertures 121 are provided in the sandpaper sheet 99, registering with and directly axially opposite apertures 120, to pass the dust particles upwardly through the sandpaper at these aperture locations and into apertures 120 in the head, and then upwardly through those apertures into the interior of shroud 103.

To place the tool of FIGS. 9 to 11 in use, an operator grips the handle, body 81, and in doing so automatically presses downwardly on an upper depressible platelike element 122 which operates an inlet valve for admitting compressed air from source 87 to motor 82. The body is so manipulated as to move sandpaper disc 99 into engagement with the work surface 105, with edge 104 of the shroud annularly engaging the work surface about the sanding head. The air discharging from motor 82 through tube 88 is exhausted leftwardly from the end 115 of inner tube 114 of the aspirator 89, and causes a corresponding leftward movement of air within tube 108 and about tube 114 by aspirator action, thus creating a partial vacuum or suction within shroud 103 drawing abraded particles upwardly from work surface 105 through space 119 about head 90 and through apertures 120 and 121. The work surface is thus kept clean, the dust is prevented from escaping into the atmosphere, and the provision of the aspirator and collection bag 118 in the exhaust line from the motor substantially reduces the noise produced by the motor.

Another possible form of the invention which will be understood without the necessity for further illustration is one in which the sanding head 90 of FIG. is driven rotatably about axis 85 by motor 82, rather than being oscillated orbitally as above discussed. In this event, head 90 would be concentric with shroud 103, rather than eccentric as illustrated in FIG. 11, but with the aspirator still functioning to produce a suction drawing air and dust particles upwardly through a space about and apertures in the rotary head and then from within the shroud to bag 118.

While certain specific embodiments of the present invention have been disclosed as typical, the invention is of course not limited to these particular forms, but rather is applicablebroadly to all such variations as fall within the scope of the appended claims.

I claim:

1. A portable abrading tool comprising a body structure; a unit movable relative to said body structure to abrade a work surface; an air motor for moving said unit and containing and forming a motor chamber through which compressed air flows; said motor including a movable part in said chamber which is driven by said compressed air and in turn drives said unit; and an aspirator structure located outside and downstream of said motor chamber and defining primary and secondary air flow paths which meet in aspirating relation outside the confines of said motor chamber; said primary air flow path being connected to said chamber to receive air discharged therefrom after it has driven said movable part; said secondary air flow path being in communication with the work surface to direct a secondary flow of air, and particles abraded from the work surface, to a location of aspirating contact with said motor discharge air beyond said motor chamber, in a relation inducing the flow of air and particles along said secondary path by movement of said motor discharge air; said aspirator structure being constructed and located to direct said primary flow of motor discharge air into contact with said secondary flow of air and abraded particles downstream of and only after said discharge air has left said chamber and in a relation thereby avoiding flow of said secondary air and particles through said chamber or into contact with said movable part.

2. A A portable abrading tool as recited inclaim 1, in which said aspirator structure includes a conduit at the outside of said motor chamber communicating through a first inlet end with the work surface to receive air and abraded particles therefrom, and through which conduit said air and abraded particles flow in a predetermined direction toward a second discharge end of the conduit, said aspirator structure including means defining a portion of said primary air flow path and receiving air discharged from and downstream of said chamber and forming an opening through which the motor discharge air is emitted at high velocity into said conduit in said predetermined direction toward said outlet end of the conduit to induce said secondary flow of air and particles through the conduit, said movable unit for abrading a work surface containing an air passage having a vsuction end located closely adjacent the work surface and through which said aspirator structure withdraws air and abraded particles from the work surface by suction.

3. A portable abrading tool comprising a body structure; a unit movable relative to said body structure -to abrade a work surface; an air motor for moving said unit and containing and forming a motor chamber through which compressed air flows; said motor including a rotor in said chamber which is driven rotatably relative to the chamber by said compressed air, and which in turn drives said unit; and an aspirator structure located outside of said motor chamber and defining primary and secondary air flow paths which meet in aspirating relation downstream of said motor chamber; said primary air flow path being connected to said chamber to receive air discharged there-from after it has driven said rotor, said secondary air flow path being in communication with the work surface to direct a secondary flow of air, and particles abraded from the work surface, to a location of aspirating contact with said motor discharge air downstream of said motor chamber, in a relation inducing the flow of air and particles along secondary path by movement of said motor discharge air; said aspirator structure being constructed, and located outside of said motor chamber, to direct said primary flow of motor discharge air into contact with said secondary flow of air and abraded particles only after said discharge air has left said chamber, and in a relation thereby avoiding flow of said secondary air and particles through said chamber or into contact with said rotor.

4. A portable abrading tool as recited in claim 3, including a porous dust collection bag to which air and abraded particles are discharged from said aspirator structure, said movable unit including a shoe carrying a sheet of abrasive material and containing a passage for receiving air and abraded particles from the work surface, said aspirator structure being carried by said body structure, and there being a flexible conduit connected to a first end to said shoe to receive air and particles from said passage therein and connected at its opposite end to said aspirator structure to deliver said air and particles thereto as said secondary flow.

5. A portable abrading tool comprising a body structure; a unit movable relative to said body structure to abrade a work surface; an air motor for moving said unit and containing and forming a motor chamber through which compressed air flows; said motor including a movable part in said chamber. which is driven by said compressed air and in turn drives said unit; and an aspirator structure located outside of said motor chamber and defining primary and secondary air flow paths which meet in aspirating relation; said primary air flow path being connected to said chamber to receive air discharged therefrom after it has driven said movable part; saidsecondary air flow path being in communication with the work surface to direct a secondary flow of air, and particles abraded from the work surface, to a location of aspirating contact with said motor discharge air, in a relation inducing the flow of air and particles along said secondary path by movement of said motor discharge air; said secondary flow of air and abraded particles meeting said primary flow of motor discharge air only after said discharge air has left said chamber in a relation thereby avoiding flow of said secondary air and particles through said chamber or into contact with said movable part, said aspirator structure including a tube at the outside of and downstream of said motor chamber and containing and defining a portion of said primary air flow path and having an outlet end through which air discharged from said motor leaves said tube, said aspirator structure including a conduit disposed about said tube in spaced relation and defining a portion of said secondary air flow path between the tube and conduit through which a flow of air is induced by the aspirator action of air discharging from said outlet end of the tube.

6. A portable abrading tool as recited in claim 4, in which said conduit increases in cross-sectional area at approximately said outlet end of said tube.

7. A portable abrading tool as recited in claim 4, in which said conduit has a portion flaring progressively to an increased diameter, said tube having a discharge end projecting into said flaring portion of the conduit and terminating at said outlet at approximately the location at which said conduit reaches its maximum diameter.

8. A portable abrading tool as recited in claim 4, in which said conduit has a portion flaring progressively to an increased diameter, said tube having a discharge end projecting into said flaring portion of the conduit and terminating at approximately the location at which said conduit reaches its maximum diameter, said conduit having a first essentially uniform diameter straight cylindrical portion upstream of and merging with and aligned axially with said flaring portion, and having a second and larger diameter essentially straight cylindrical portion downstream of and merging with and aligned axially with said flaring portion of the conduit.

9. A portable abrading tool comprising a body structure; a unit movable relative to said body structure to abrade a work surface; an air motor for moving said unit and containing and forming a motor chamber through which compressed air flows; said motor including a movable part in said chamber which is driven by said compressed air and in turn drives said unit; and an aspirator structure located outside of said motor chamber and defining primary and secondary air flow paths which meet in aspirating relation; said primary air flow path being connected to said chamber to receive air discharged therefrom after it has driven said movable part; said secondary air flow path being in communication with the work surface to direct a secondary flow of air, and particles abraded from the work surface, to a location of aspirating contact with said motor discharge air, in a relation inducing the flow of air and particles along said secondary path by movement of said motor discharge air; said secondary flow of air and abraded particles meeting said primary flow of motor discharge air only after said discharge air has left said chamber in a relation thereby avoiding flow of said secondary air and particles through said chamber or into contract with said movable part, said movable unit including a cushion having a working face adjacent which a sheet of abrasive material is carried in use, said cushion containing one or more air passages opening through said working face of the cushion to a location adjacent the sheet of abrasive material and through which said aspirator structure withdraws air and abraded particles by suction from near the work surface, said passages in said cushion being defined as apertures extending through the cushion from an upper side thereof to said working face, and communicating recesses formed in said upper side of the cushion, there being a plate extending across the upper side of the cushion and closing said recesses at that location.

10. A portable abrading tool as recited in claim 8, including said sheet of abrasive material as an element of the claim, said sheet containing apertures communicating with said passages in the cushion.

11. A portable abrading tool comprising a body structure; a unit movable relative to said body structure to abrade a work surface; an air motor for moving said unit and containing and forming a motor chamber through which compressed air flows; said motor including a movable part in said chamber which is driven by said compressed air and in turn drives said unit; and an aspirator structure located outside of said motor chamber and defining primary and secondary air flow paths which meet in aspirating relation; said primary air flow path being connected to said chamber to receive air discharged therefrom after it has driven said movable part; said secondary air flow path being in communication with the work surface to direct a secondary flow of air, and particles abraded from the work surface, to a location of aspirating contact with said motor discharge air, in a relation inducing the flow of air and particles along said secondary path by movement of said motor discharge air; said secondary flow of air and abraded particles meeting said primary flow of motor discharge air only after said discharge air has left said chamber in a relation thereby avoiding flow of said secondary air and particles through said chamber or into contact with said movable part, said movable unit containing at least one passage for receiving abraded particles from the work surface, said aspirator structure being carried by said body structure, there being a flexible conduit connected. at a first end to said movable unit to receive air and particles from said passage therein and connected at its opposite end to said aspirator structure to deliver air and particles thereto as said secondary flow.

12. A portable abrading tool comprising a body structure; a unit movable relative to said body structure to abrade a work surface; an air motor for moving said unit and containing and forming a motor chamber through which compressed air flows; said motor including a movable part in said chamber which is driven by said compressed air and in turn drives said unit; and an aspirator structure located outside of said motor chamber and defining primary and secondary air flow paths which meet in aspirating relation; said primary air flow path being connected to said chamber to receive air discharged therefrom after it has driven said movable part; said secondary air flow path being in communication with the work surface to direct a secondary flow of air, and particles abraded from the work surface, to a location of aspirating contact with said motor discharge air, in a relation inducing the flow of air and particles along said secondary path by movement of said motor discharge air; said secondary flow of air and abraded particles meeting said primary flow of motor discharge air only after said discharge air has left said chamber in a relation thereby avoiding flow of said secondary air and particles through said chamber or into contact with said movable part, said movable unit including a working shoe which, when the tool is utilized for abrading an upwardly facing horizonal work surface, extends essentially horizontally at the upper side of said work surface, and which carries at its underside a sheet of abrasive material for contacting the work surface, said shoe containing at least one passage through which air and abraded particles flow from the work surface, said body structure including a body part extending essentially horizontally at a location spaced above said shoe and carrying said aspirator structure, there being a flexible conduit connected at one end to said passage in the shoe and connected at its opposite end to said aspirator structure to ,conduct air and abraded particles from the shoe passage through said flexible conduit to the aspirator structure.

13. A portable abrading tool as recited in claim 11, in which said aspirator structure includes a second conduit carried at the upper side of said body part and extending generally horizontally at that location and through which said flow of air and abraded particles from said flexible conduit flow in a predetermined direction, and a third conduit leading from said motor chamber and emitting said motor discharge air into said second conduit in said predetermined direction to induce the flow of said air and particles from the work surface, there being a porous particle entrapment bag into which air and entrained abraded particles are delivered from said aspirator structure and formed of a porous material through which said air can escape while entrapping said particles in the bag.

14. A portable abrading tool comprising a body structure; a unit movable relative to said body structure to abrade a work surface; an air motor for moving said unit and containing said forming a motor chamber through which compressed air flows; said motor including a movable part in said chamber which is driven by said compressed air and in turn drives said unit; and an aspirator structure located outside of said motor chamber and defining primary and secondary air flow paths which meet in aspirating relation; said primary air flow path being connected to said chamber to receive air discharged therefrom after it has driven said movable part; said secondary air flow path being in communication with the work surface to direct a secondary flow of air, and particles abraded from the work surface, to a location of aspirating contact with said motor discharge air, in a relation inducing the flow of air and particles along said secondary path by movement of said motor discharge air; said secondary flow of air and abraded particles meeting said primary flow of motor discharge air only after said discharge air has left said chamber in a relation thereby avoiding flow of said secondary air and particles through said chamber or into contact with said movable part, said movable unit being a circular head power driven by said motor at the underside of said body structure and carrying an abrasive disc, there being an essentially circular shroud of deformable material extending about said circular head to contact the work surface essentially thereabout and defining an essentially closed space communicating with the aspirator structure and communicating with the work surface through passages in said head and through a space radially between the head and shroud to withdraw air and particles from the work surface to the aspirator structure.

15. A portable abrading tool as recited in claim 13, including means mounting said shroud adjustably to said body structure for movement relative thereto and relative to said circular head and toward and away from said work surface.

16. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface and containing a space within which a moving part is located and through which a primary flow of air passes, and an aspirator through which said primary flow of air passes after it leaves said space in the motor and which is energized by said primary flow to induce a secondary flow of air and abraded particles to said aspirator without passage of said secondary flow through said space or in contact with said moving part, said work abrading unit containing a suction passage through which said secondary flow passes, said aspirator being carried by said body, there being a flexible conduit for conducting said secondary flow of air and particles from said unit to said #EUNITED STA'lES PATENT OFFICE CERTIFICATE'OF CORRECTION Patent No. 3,7 5, 09 Dated January 15, l en I I 5 Alma A; Hutchins It is certified that error appears in the above identified United States Letters Patent and that said Letters Patent'are hereby corrected as follows t In claim 4, line 9, "to", first occurrence, should read-at-'. Inclaims 6, 7 and 8, line 1 in each, the claim reference numeral "'4'? should read-5- In claim 10, line 1, the claim reference numeral "8" should read--9. In claim 13, line 1, the claim reference numeral "11 should read--l2--. In claim 14, line 4, the word "said" should read-and--. 1 In claim 15, line 1, the claim reference numeral "13" should read-l4-..

Signed and sealed this 29th day of October 1974.

I (SEAL) Attest:

1 McCOY M. cIBsoNJR. c. MARSHALL DANN Attesting Officer Commissioner of Patents 

1. A portable abrading tool comprising a body structure; a unit movable relative to said body structure to abrade a work surface; an air motor for moving said unit and containing and forming a motor chamber through which compressed air flows; said motor including a movable part in said chamber which is driven by said compressed air and in turn drives said unit; and an aspirator structure located outside and downstream of said motor chamber and defining primary and secondary air flow paths which meet in aspirating relation outside the confines of said motor chamber; said primary air flow path being connected to said chamber to receive air discharged therefrom after it has driven said movable part; said secondary air flow path being in communication with the work surface to direct a secondary flow of air, and particles abraded from the work surface, to a location of aspirating contact with said motor discharge air beyond said motor chamber, in a relation inducing the flow of air and particles along said secondary path by movement of said motor discharge air; said aspirator structure being constructed and located to direct said primary flow of motor discharge air into contact with said secondary flow of air and abraded particles downstream of and only after said discharGe air has left said chamber and in a relation thereby avoiding flow of said secondary air and particles through said chamber or into contact with said movable part.
 2. A portable abrading tool as recited in claim 1, in which said aspirator structure includes a conduit at the outside of said motor chamber communicating through a first inlet end with the work surface to receive air and abraded particles therefrom, and through which conduit said air and abraded particles flow in a predetermined direction toward a second discharge end of the conduit, said aspirator structure including means defining a portion of said primary air flow path and receiving air discharged from and downstream of said chamber and forming an opening through which the motor discharge air is emitted at high velocity into said conduit in said predetermined direction toward said outlet end of the conduit to induce said secondary flow of air and particles through the conduit, said movable unit for abrading a work surface containing an air passage having a suction end located closely adjacent the work surface and through which said aspirator structure withdraws air and abraded particles from the work surface by suction.
 3. A portable abrading tool comprising a body structure; a unit movable relative to said body structure to abrade a work surface; an air motor for moving said unit and containing and forming a motor chamber through which compressed air flows; said motor including a rotor in said chamber which is driven rotatably relative to the chamber by said compressed air, and which in turn drives said unit; and an aspirator structure located outside of said motor chamber and defining primary and secondary air flow paths which meet in aspirating relation downstream of said motor chamber; said primary air flow path being connected to said chamber to receive air discharged there-from after it has driven said rotor, said secondary air flow path being in communication with the work surface to direct a secondary flow of air, and particles abraded from the work surface, to a location of aspirating contact with said motor discharge air downstream of said motor chamber, in a relation inducing the flow of air and particles along secondary path by movement of said motor discharge air; said aspirator structure being constructed, and located outside of said motor chamber, to direct said primary flow of motor discharge air into contact with said secondary flow of air and abraded particles only after said discharge air has left said chamber, and in a relation thereby avoiding flow of said secondary air and particles through said chamber or into contact with said rotor.
 4. A portable abrading tool as recited in claim 3, including a porous dust collection bag to which air and abraded particles are discharged from said aspirator structure, said movable unit including a shoe carrying a sheet of abrasive material and containing a passage for receiving air and abraded particles from the work surface, said aspirator structure being carried by said body structure, and there being a flexible conduit connected to a first end to said shoe to receive air and particles from said passage therein and connected at its opposite end to said aspirator structure to deliver said air and particles thereto as said secondary flow.
 5. A portable abrading tool comprising a body structure; a unit movable relative to said body structure to abrade a work surface; an air motor for moving said unit and containing and forming a motor chamber through which compressed air flows; said motor including a movable part in said chamber which is driven by said compressed air and in turn drives said unit; and an aspirator structure located outside of said motor chamber and defining primary and secondary air flow paths which meet in aspirating relation; said primary air flow path being connected to said chamber to receive air discharged therefrom after it has driven said movable part; said secondary air flow path being in communication with the work Surface to direct a secondary flow of air, and particles abraded from the work surface, to a location of aspirating contact with said motor discharge air, in a relation inducing the flow of air and particles along said secondary path by movement of said motor discharge air; said secondary flow of air and abraded particles meeting said primary flow of motor discharge air only after said discharge air has left said chamber in a relation thereby avoiding flow of said secondary air and particles through said chamber or into contact with said movable part, said aspirator structure including a tube at the outside of and downstream of said motor chamber and containing and defining a portion of said primary air flow path and having an outlet end through which air discharged from said motor leaves said tube, said aspirator structure including a conduit disposed about said tube in spaced relation and defining a portion of said secondary air flow path between the tube and conduit through which a flow of air is induced by the aspirator action of air discharging from said outlet end of the tube.
 6. A portable abrading tool as recited in claim 4, in which said conduit increases in cross-sectional area at approximately said outlet end of said tube.
 7. A portable abrading tool as recited in claim 4, in which said conduit has a portion flaring progressively to an increased diameter, said tube having a discharge end projecting into said flaring portion of the conduit and terminating at said outlet at approximately the location at which said conduit reaches its maximum diameter.
 8. A portable abrading tool as recited in claim 4, in which said conduit has a portion flaring progressively to an increased diameter, said tube having a discharge end projecting into said flaring portion of the conduit and terminating at approximately the location at which said conduit reaches its maximum diameter, said conduit having a first essentially uniform diameter straight cylindrical portion upstream of and merging with and aligned axially with said flaring portion, and having a second and larger diameter essentially straight cylindrical portion downstream of and merging with and aligned axially with said flaring portion of the conduit.
 9. A portable abrading tool comprising a body structure; a unit movable relative to said body structure to abrade a work surface; an air motor for moving said unit and containing and forming a motor chamber through which compressed air flows; said motor including a movable part in said chamber which is driven by said compressed air and in turn drives said unit; and an aspirator structure located outside of said motor chamber and defining primary and secondary air flow paths which meet in aspirating relation; said primary air flow path being connected to said chamber to receive air discharged therefrom after it has driven said movable part; said secondary air flow path being in communication with the work surface to direct a secondary flow of air, and particles abraded from the work surface, to a location of aspirating contact with said motor discharge air, in a relation inducing the flow of air and particles along said secondary path by movement of said motor discharge air; said secondary flow of air and abraded particles meeting said primary flow of motor discharge air only after said discharge air has left said chamber in a relation thereby avoiding flow of said secondary air and particles through said chamber or into contract with said movable part, said movable unit including a cushion having a working face adjacent which a sheet of abrasive material is carried in use, said cushion containing one or more air passages opening through said working face of the cushion to a location adjacent the sheet of abrasive material and through which said aspirator structure withdraws air and abraded particles by suction from near the work surface, said passages in said cushion being defined as apertures extending through the cushion from an upper side thereof to said working face, aNd communicating recesses formed in said upper side of the cushion, there being a plate extending across the upper side of the cushion and closing said recesses at that location.
 10. A portable abrading tool as recited in claim 8, including said sheet of abrasive material as an element of the claim, said sheet containing apertures communicating with said passages in the cushion.
 11. A portable abrading tool comprising a body structure; a unit movable relative to said body structure to abrade a work surface; an air motor for moving said unit and containing and forming a motor chamber through which compressed air flows; said motor including a movable part in said chamber which is driven by said compressed air and in turn drives said unit; and an aspirator structure located outside of said motor chamber and defining primary and secondary air flow paths which meet in aspirating relation; said primary air flow path being connected to said chamber to receive air discharged therefrom after it has driven said movable part; said secondary air flow path being in communication with the work surface to direct a secondary flow of air, and particles abraded from the work surface, to a location of aspirating contact with said motor discharge air, in a relation inducing the flow of air and particles along said secondary path by movement of said motor discharge air; said secondary flow of air and abraded particles meeting said primary flow of motor discharge air only after said discharge air has left said chamber in a relation thereby avoiding flow of said secondary air and particles through said chamber or into contact with said movable part, said movable unit containing at least one passage for receiving abraded particles from the work surface, said aspirator structure being carried by said body structure, there being a flexible conduit connected at a first end to said movable unit to receive air and particles from said passage therein and connected at its opposite end to said aspirator structure to deliver air and particles thereto as said secondary flow.
 12. A portable abrading tool comprising a body structure; a unit movable relative to said body structure to abrade a work surface; an air motor for moving said unit and containing and forming a motor chamber through which compressed air flows; said motor including a movable part in said chamber which is driven by said compressed air and in turn drives said unit; and an aspirator structure located outside of said motor chamber and defining primary and secondary air flow paths which meet in aspirating relation; said primary air flow path being connected to said chamber to receive air discharged therefrom after it has driven said movable part; said secondary air flow path being in communication with the work surface to direct a secondary flow of air, and particles abraded from the work surface, to a location of aspirating contact with said motor discharge air, in a relation inducing the flow of air and particles along said secondary path by movement of said motor discharge air; said secondary flow of air and abraded particles meeting said primary flow of motor discharge air only after said discharge air has left said chamber in a relation thereby avoiding flow of said secondary air and particles through said chamber or into contact with said movable part, said movable unit including a working shoe which, when the tool is utilized for abrading an upwardly facing horizonal work surface, extends essentially horizontally at the upper side of said work surface, and which carries at its underside a sheet of abrasive material for contacting the work surface, said shoe containing at least one passage through which air and abraded particles flow from the work surface, said body structure including a body part extending essentially horizontally at a location spaced above said shoe and carrying said aspirator structure, there being a flexible conduit connected at one end to said passage in the shoe and connected at its opposite end to said asPirator structure to conduct air and abraded particles from the shoe passage through said flexible conduit to the aspirator structure.
 13. A portable abrading tool as recited in claim 11, in which said aspirator structure includes a second conduit carried at the upper side of said body part and extending generally horizontally at that location and through which said flow of air and abraded particles from said flexible conduit flow in a predetermined direction, and a third conduit leading from said motor chamber and emitting said motor discharge air into said second conduit in said predetermined direction to induce the flow of said air and particles from the work surface, there being a porous particle entrapment bag into which air and entrained abraded particles are delivered from said aspirator structure and formed of a porous material through which said air can escape while entrapping said particles in the bag.
 14. A portable abrading tool comprising a body structure; a unit movable relative to said body structure to abrade a work surface; an air motor for moving said unit and containing said forming a motor chamber through which compressed air flows; said motor including a movable part in said chamber which is driven by said compressed air and in turn drives said unit; and an aspirator structure located outside of said motor chamber and defining primary and secondary air flow paths which meet in aspirating relation; said primary air flow path being connected to said chamber to receive air discharged therefrom after it has driven said movable part; said secondary air flow path being in communication with the work surface to direct a secondary flow of air, and particles abraded from the work surface, to a location of aspirating contact with said motor discharge air, in a relation inducing the flow of air and particles along said secondary path by movement of said motor discharge air; said secondary flow of air and abraded particles meeting said primary flow of motor discharge air only after said discharge air has left said chamber in a relation thereby avoiding flow of said secondary air and particles through said chamber or into contact with said movable part, said movable unit being a circular head power driven by said motor at the underside of said body structure and carrying an abrasive disc, there being an essentially circular shroud of deformable material extending about said circular head to contact the work surface essentially thereabout and defining an essentially closed space communicating with the aspirator structure and communicating with the work surface through passages in said head and through a space radially between the head and shroud to withdraw air and particles from the work surface to the aspirator structure.
 15. A portable abrading tool as recited in claim 13, including means mounting said shroud adjustably to said body structure for movement relative thereto and relative to said circular head and toward and away from said work surface.
 16. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface and containing a space within which a moving part is located and through which a primary flow of air passes, and an aspirator through which said primary flow of air passes after it leaves said space in the motor and which is energized by said primary flow to induce a secondary flow of air and abraded particles to said aspirator without passage of said secondary flow through said space or in contact with said moving part, said work abrading unit containing a suction passage through which said secondary flow passes, said aspirator being carried by said body, there being a flexible conduit for conducting said secondary flow of air and particles from said unit to said aspirator. 